A beam-type load cell generally comprises a beam of high strength steel or aluminum, on which are mounted a number of strain gauges which produce an electrical signal in response to a downward deflection of the beam caused by weight on the load cell. In a typical application, a plurality of load cells are used to support a weigh platform deck, onto which a vehicle to be weighed, typically a truck, is positioned. The weight of the vehicle causes a downward deflection of the metal beam of each load cell, creating stress in the beam. The strain gauges, which are arranged in various combinations, typically in the vicinity of the opposite ends of the load cell, measure the stress and produce a corresponding electrical output. The electrical output of the strain gauges at each end of each individual load cell is adjusted, and the outputs of all the load cells are then combined so that the total output is accurately indicative of the weight of the vehicle positioned on the platform.
There has been a significant amount of effort in the load cell art to improve both the accuracy and the reproducability of results produced by the load cell. In addition, attempts have been made to improve the durability of the load cell, so that it is capable of operating in adverse conditions, such as, for instance, under water for extended periods of time. One line of development in the art has been a so-called "floating" load cell, as evidenced by U.S. Pat. No. 4,281,781 titled VEHICLE PLATFORM SCALE. A floating load cell is characterized by being freely supported off of its respective ends, typically by means of a pin which is positioned in a groove in the lower surface of the load cell. In such a load configuration, the ends of the load cell are not bolted or otherwise rigidly fixed in position, so that the load cell is free to deflect downwardly about the supporting pins. However, even in a floating load cell, it is still necessary to support the ends of the load cell and to prevent the load cell from lifting off the pin. Previous attempts to provide such support, however, have significant disadvantages. The support assemblies have generally been bulky and relatively expensive. Further, and perhaps most importantly, the results of weigh platforms using such support assemblies for the load cells have been characterized by severe inaccuracies, due to uneven surfaces on which the load cell is positioned and collection of debris in the support assemblies.
Accordingly, the inventor has developed a load cell assembly which incorporates a particular structural arrangement for supporting the ends of a floating (freely supported) load cell. The load cell assembly described herein provides accurate, reproducible results and is capable of operating for extended periods under harsh operating conditions, including under water.